diff --git a/app/src/main/java/com/m57/hermescontrol/data/model/SessionListResponse.kt b/app/src/main/java/com/m57/hermescontrol/data/model/SessionListResponse.kt
index 5e2a6985..e01e6e0b 100644
--- a/app/src/main/java/com/m57/hermescontrol/data/model/SessionListResponse.kt
+++ b/app/src/main/java/com/m57/hermescontrol/data/model/SessionListResponse.kt
@@ -83,6 +83,10 @@ data class SessionInfo(
     // Uses LenientNullableBooleanSerializer to tolerate both JSON booleans and raw SQLite ints (issue #966).
     @Serializable(with = LenientNullableBooleanSerializer::class)
     val pinned: Boolean? = null,
+    // Session-level hidden flag (issue #1019): background agent sessions or internal routines.
+    // Uses LenientNullableBooleanSerializer to tolerate booleans, raw SQLite ints (0/1), and strings.
+    @Serializable(with = LenientNullableBooleanSerializer::class)
+    val hidden: Boolean? = null,
 )
 
 @Serializable
@@ -95,10 +99,11 @@ data class SessionStatsResponse(
 
 @Serializable
 data class SessionRenameRequest(
-    // Both fields are optional: the backend PATCH accepts any subset
-    // (SessionRename model: title/archived/pinned, omitted = unchanged).
+    // All fields are optional: the backend PATCH accepts any subset
+    // (SessionRename model: title/archived/pinned/hidden, omitted = unchanged).
     val title: String? = null,
     val pinned: Boolean? = null,
+    val hidden: Boolean? = null,
 )
 
 @Serializable
diff --git a/app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt b/app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt
index 2f81b314..e6d5149c 100644
--- a/app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt
+++ b/app/src/main/java/com/m57/hermescontrol/data/remote/HermesApiService.kt
@@ -216,6 +216,14 @@ interface HermesApiService {
         @Body body: SessionRenameRequest,
     ): Response<Unit>
 
+    // Hide/unhide rides the same PATCH /api/sessions/{id} — body carries only
+    // {hidden} (backend SessionRename model, any subset accepted; issue #1019).
+    @PATCH("api/sessions/{id}")
+    suspend fun setSessionHidden(
+        @Path("id", encoded = true) sessionId: String,
+        @Body body: SessionRenameRequest,
+    ): Response<Unit>
+
     @POST("api/sessions/bulk-delete")
     suspend fun bulkDeleteSessions(
         @Body body: BulkDeleteRequest,
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsScreen.kt b/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsScreen.kt
index a905cca3..bcefaa5b 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsScreen.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsScreen.kt
@@ -46,6 +46,8 @@ import androidx.compose.material.icons.filled.PushPin
 import androidx.compose.material.icons.filled.Search
 import androidx.compose.material.icons.filled.SelectAll
 import androidx.compose.material.icons.filled.Terminal
+import androidx.compose.material.icons.filled.Visibility
+import androidx.compose.material.icons.filled.VisibilityOff
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Badge
 import androidx.compose.material3.BadgedBox
@@ -59,6 +61,7 @@ import androidx.compose.material3.DropdownMenu
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.FilledTonalButton
 import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.OutlinedButton
 import androidx.compose.material3.OutlinedTextField
@@ -290,7 +293,7 @@ private fun displayedSessions(state: SessionsUiState): List<SessionTreeItem> =
             )
         }
     } else {
-        flattenSessionTree(state.sessions)
+        flattenSessionTree(state.displaySessions)
     }
 
 @OptIn(ExperimentalFoundationApi::class)
@@ -313,6 +316,7 @@ fun SessionsScreen(
             state.isSearchMode,
             state.searchQuery,
             state.sessions,
+            state.showHidden,
             state.searchResults,
         ) {
             displayedSessions(state)
@@ -521,6 +525,29 @@ fun SessionsScreen(
         navigationIcon = onOpenDrawer?.let { NavIcon.Menu(it) },
         isRefreshing = state.isLoading,
         onRefresh = { viewModel.loadSessions() },
+        actions = {
+            if (state.hasHiddenSessions) {
+                IconButton(
+                    onClick = { viewModel.toggleShowHidden() },
+                    modifier = Modifier.testTag("sessions_action_toggle_hidden"),
+                ) {
+                    Icon(
+                        imageVector =
+                            if (state.showHidden) {
+                                Icons.Filled.VisibilityOff
+                            } else {
+                                Icons.Filled.Visibility
+                            },
+                        contentDescription =
+                            if (state.showHidden) {
+                                stringResource(R.string.sessions_hide_hidden)
+                            } else {
+                                stringResource(R.string.sessions_show_hidden)
+                            },
+                    )
+                }
+            }
+        },
         modifier = modifier,
     ) {
         // Single scrolling column: search bar pinned on top, list fills below.
@@ -685,6 +712,16 @@ fun SessionsScreen(
                         )
                     }
 
+                    state.displaySessions.isEmpty() -> {
+                        EmptyState(
+                            title = stringResource(R.string.history_empty_title),
+                            subtitle = stringResource(R.string.sessions_all_hidden_desc),
+                            icon = Icons.Filled.VisibilityOff,
+                            actionLabel = stringResource(R.string.sessions_show_hidden),
+                            onAction = { viewModel.toggleShowHidden() },
+                        )
+                    }
+
                     else -> {
                         Column(modifier = Modifier.fillMaxSize()) {
                             // ── Stats row ───────────────────────────────────────
@@ -801,6 +838,7 @@ fun SessionsScreen(
                                         isSelected = session.id in state.selectedIds,
                                         isDeleting = session.id in state.deletingSessionIds,
                                         isPinned = session.pinned == true,
+                                        isHidden = session.hidden == true,
                                         highlightBackground = primaryContainer,
                                         highlightForeground = onPrimaryContainer,
                                         onCardClick = {
@@ -822,6 +860,7 @@ fun SessionsScreen(
                                             )
                                         },
                                         onTogglePin = { viewModel.togglePin(session.id) },
+                                        onToggleHide = { viewModel.toggleHide(session.id) },
                                         onDelete = { viewModel.requestDeleteSession(session.id) },
                                     )
                                 }
@@ -969,6 +1008,7 @@ private fun SessionCard(
     isSelected: Boolean,
     isDeleting: Boolean,
     isPinned: Boolean,
+    isHidden: Boolean = false,
     highlightBackground: Color,
     highlightForeground: Color,
     onCardClick: () -> Unit,
@@ -976,6 +1016,7 @@ private fun SessionCard(
     onSelect: () -> Unit,
     onRename: () -> Unit,
     onTogglePin: () -> Unit,
+    onToggleHide: () -> Unit,
     onDelete: () -> Unit,
 ) {
     val spacing = LocalSpacing.current
@@ -1095,6 +1136,13 @@ private fun SessionCard(
                             style = MaterialTheme.typography.bodySmall,
                             color = MaterialTheme.colorScheme.onSurfaceVariant,
                         )
+                        if (session.hidden == true) {
+                            Spacer(modifier = Modifier.width(spacing.sm))
+                            StatusBadge(
+                                text = stringResource(R.string.sessions_hidden_badge),
+                                status = StatusBadgeType.NEUTRAL,
+                            )
+                        }
                         if (!session.status.isNullOrBlank()) {
                             Spacer(modifier = Modifier.width(spacing.sm))
                             StatusBadge(
@@ -1116,6 +1164,11 @@ private fun SessionCard(
                     menuExpanded = false
                     onTogglePin()
                 },
+                isHidden = isHidden,
+                onToggleHide = {
+                    menuExpanded = false
+                    onToggleHide()
+                },
                 onSelect = {
                     menuExpanded = false
                     onSelect()
@@ -1301,6 +1354,8 @@ private fun SessionActionMenu(
     isDeleting: Boolean,
     isPinned: Boolean = false,
     onTogglePin: (() -> Unit)? = null,
+    isHidden: Boolean = false,
+    onToggleHide: (() -> Unit)? = null,
     onSelect: () -> Unit,
     onRename: () -> Unit,
     onDelete: () -> Unit,
@@ -1324,6 +1379,33 @@ private fun SessionActionMenu(
                 onClick = onTogglePin,
             )
         }
+        if (onToggleHide != null) {
+            DropdownMenuItem(
+                text = {
+                    Text(
+                        stringResource(
+                            if (isHidden) {
+                                R.string.sessions_action_unhide
+                            } else {
+                                R.string.sessions_action_hide
+                            },
+                        ),
+                    )
+                },
+                leadingIcon = {
+                    Icon(
+                        imageVector =
+                            if (isHidden) {
+                                Icons.Filled.Visibility
+                            } else {
+                                Icons.Filled.VisibilityOff
+                            },
+                        contentDescription = null,
+                    )
+                },
+                onClick = onToggleHide,
+            )
+        }
         DropdownMenuItem(
             text = { Text(stringResource(R.string.sessions_action_select)) },
             leadingIcon = { Icon(Icons.Filled.CheckCircle, contentDescription = null) },
diff --git a/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsViewModel.kt b/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsViewModel.kt
index 7b0c9308..e8182e00 100644
--- a/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsViewModel.kt
+++ b/app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsViewModel.kt
@@ -89,8 +89,15 @@ data class SessionsUiState(
     val isSearching: Boolean = false,
     val searchResults: List<SessionSearchResult> = emptyList(),
     val searchError: String? = null,
+    val showHidden: Boolean = false,
 ) {
     val isSearchMode: Boolean get() = searchQuery.isNotBlank()
+
+    val hasHiddenSessions: Boolean
+        get() = sessions.any { it.hidden == true }
+
+    val displaySessions: List<SessionInfo>
+        get() = if (showHidden) sessions else sessions.filter { it.hidden != true }
 }
 
 class SessionsViewModel :
@@ -315,6 +322,10 @@ class SessionsViewModel :
 
     // ── Bulk selection ───────────────────────────────────────────────────
 
+    fun toggleShowHidden() {
+        _uiState.update { it.copy(showHidden = !it.showHidden) }
+    }
+
     fun toggleSelecting() {
         _uiState.update {
             it.copy(
@@ -455,6 +466,49 @@ class SessionsViewModel :
         }
     }
 
+    // ── Hide / unhide (issue #1019) ──────────────────────────────────────
+
+    /**
+     * Toggle the hidden flag on a session via PATCH /api/sessions/{id} ({hidden}).
+     */
+    fun toggleHide(sessionId: String) {
+        val session = _uiState.value.sessions.find { it.id == sessionId } ?: return
+        val targetHidden = session.hidden != true
+        viewModelScope.launch {
+            val result =
+                safeApiCall {
+                    ApiClient.hermesApi.setSessionHidden(
+                        sessionId = sessionId,
+                        body = SessionRenameRequest(hidden = targetHidden),
+                    )
+                }
+            when (result) {
+                is NetworkResult.Success -> {
+                    _uiState.update {
+                        it.copy(
+                            sessions =
+                                it.sessions
+                                    .map { s -> if (s.id == sessionId) s.copy(hidden = targetHidden) else s }
+                                    .pinnedFirst(),
+                            toastMessage =
+                                if (targetHidden) {
+                                    "Session hidden"
+                                } else {
+                                    "Session unhidden"
+                                },
+                        )
+                    }
+                }
+
+                is NetworkResult.Failure -> {
+                    _uiState.update {
+                        it.copy(toastMessage = "Hide failed: ${result.error.message}")
+                    }
+                }
+            }
+        }
+    }
+
     // ── Delete (single) ──────────────────────────────────────────────────
 
     fun requestDeleteSession(sessionId: String) {
diff --git a/app/src/main/res/values-ko/strings.xml b/app/src/main/res/values-ko/strings.xml
index 38f2446f..a285a430 100644
--- a/app/src/main/res/values-ko/strings.xml
+++ b/app/src/main/res/values-ko/strings.xml
@@ -406,6 +406,12 @@
     <string name="sessions_action_select_all">전체 선택</string>
     <string name="sessions_action_deselect_all">선택 해제</string>
     <string name="sessions_action_delete_n">%1$d개 삭제</string>
+    <string name="sessions_action_hide">숨기기</string>
+    <string name="sessions_action_unhide">숨김 해제</string>
+    <string name="sessions_show_hidden">숨겨진 세션 표시</string>
+    <string name="sessions_hide_hidden">숨겨진 세션 숨기기</string>
+    <string name="sessions_hidden_badge">숨김</string>
+    <string name="sessions_all_hidden_desc">모든 세션이 현재 숨겨져 있습니다. 아래를 탭하여 숨겨진 세션을 표시하세요.</string>
 
     <!-- Toolsets Screen -->
     <string name="toolsets_empty_title">툴셋이 없습니다</string>
diff --git a/app/src/main/res/values-zh/strings.xml b/app/src/main/res/values-zh/strings.xml
index 9e66e094..15a976fe 100644
--- a/app/src/main/res/values-zh/strings.xml
+++ b/app/src/main/res/values-zh/strings.xml
@@ -523,6 +523,12 @@
     <string name="sessions_action_rename">重命名</string>
     <string name="sessions_action_pin">置顶</string>
     <string name="sessions_action_unpin">取消置顶</string>
+    <string name="sessions_action_hide">隐藏</string>
+    <string name="sessions_action_unhide">取消隐藏</string>
+    <string name="sessions_show_hidden">显示已隐藏的会话</string>
+    <string name="sessions_hide_hidden">隐藏已隐藏的会话</string>
+    <string name="sessions_hidden_badge">已隐藏</string>
+    <string name="sessions_all_hidden_desc">所有会话当前均已隐藏。点击下方以显示已隐藏的会话。</string>
     <string name="sessions_pinned_indicator">已置顶</string>
     <string name="sessions_fork_indicator">分支会话</string>
     <string name="sessions_rename_title">重命名会话</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index f47e7ff9..1f270a38 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -599,6 +599,12 @@
     <string name="sessions_action_rename">Rename</string>
     <string name="sessions_action_pin">Pin</string>
     <string name="sessions_action_unpin">Unpin</string>
+    <string name="sessions_action_hide">Hide</string>
+    <string name="sessions_action_unhide">Unhide</string>
+    <string name="sessions_show_hidden">Show hidden sessions</string>
+    <string name="sessions_hide_hidden">Hide hidden sessions</string>
+    <string name="sessions_hidden_badge">Hidden</string>
+    <string name="sessions_all_hidden_desc">All sessions are currently hidden. Tap below to show hidden sessions.</string>
     <string name="sessions_pinned_indicator">Pinned</string>
     <string name="sessions_fork_indicator">Forked session</string>
     <string name="sessions_rename_title">Rename Session</string>
diff --git a/app/src/test/java/com/m57/hermescontrol/data/model/ModelSerializationTest.kt b/app/src/test/java/com/m57/hermescontrol/data/model/ModelSerializationTest.kt
index 94ce2d81..2fda9252 100644
--- a/app/src/test/java/com/m57/hermescontrol/data/model/ModelSerializationTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/data/model/ModelSerializationTest.kt
@@ -312,6 +312,41 @@ class ModelSerializationTest {
         assertEquals(false, s8.pinned)
     }
 
+    @Test
+    fun testSessionInfoDeserialization_hiddenToleratesIntAndBooleanAndString() {
+        val s1 = json.decodeFromString<SessionInfo>("""{"id": "s1", "hidden": 0}""")
+        assertEquals(false, s1.hidden)
+
+        val s2 = json.decodeFromString<SessionInfo>("""{"id": "s2", "hidden": 1}""")
+        assertEquals(true, s2.hidden)
+
+        val s3 = json.decodeFromString<SessionInfo>("""{"id": "s3", "hidden": false}""")
+        assertEquals(false, s3.hidden)
+
+        val s4 = json.decodeFromString<SessionInfo>("""{"id": "s4", "hidden": true}""")
+        assertEquals(true, s4.hidden)
+
+        val s5 = json.decodeFromString<SessionInfo>("""{"id": "s5", "hidden": null}""")
+        assertNull(s5.hidden)
+
+        val s6 = json.decodeFromString<SessionInfo>("""{"id": "s6"}""")
+        assertNull(s6.hidden)
+
+        val s7 = json.decodeFromString<SessionInfo>("""{"id": "s7", "hidden": "1"}""")
+        assertEquals(true, s7.hidden)
+
+        val s8 = json.decodeFromString<SessionInfo>("""{"id": "s8", "hidden": "false"}""")
+        assertEquals(false, s8.hidden)
+    }
+
+    @Test
+    fun testSessionRenameRequestSerialization_includesHidden() {
+        val req = SessionRenameRequest(title = "new name", hidden = true)
+        val encoded = json.encodeToString(SessionRenameRequest.serializer(), req)
+        assertTrue(encoded.contains("\"hidden\":true"))
+        assertTrue(encoded.contains("\"title\":\"new name\""))
+    }
+
     @Test
     fun testSessionMessagesResponseDeserialization_missingMessages_causesNullOnNonNullableField() {
         val jsonStr = "{}"
diff --git a/app/src/test/java/com/m57/hermescontrol/ui/common/RefreshOnChangeTest.kt b/app/src/test/java/com/m57/hermescontrol/ui/common/RefreshOnChangeTest.kt
index e5f07aeb..7714b5a6 100644
--- a/app/src/test/java/com/m57/hermescontrol/ui/common/RefreshOnChangeTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/ui/common/RefreshOnChangeTest.kt
@@ -31,13 +31,19 @@ class RefreshOnChangeTest {
 
     private class TestViewModel : ViewModel() {
         val state = MutableStateFlow("initial")
+        var job: kotlinx.coroutines.Job? = null
 
         init {
-            refreshOnChange(
-                eventType = ChangeEvents.CRON,
-                apiCall = { NetworkResult.Success("refreshed") },
-                onSuccess = { state.value = it },
-            )
+            job =
+                refreshOnChange(
+                    eventType = ChangeEvents.CRON,
+                    apiCall = { NetworkResult.Success("refreshed") },
+                    onSuccess = { state.value = it },
+                )
+        }
+
+        fun cleanup() {
+            job?.cancel()
         }
     }
 
@@ -55,23 +61,31 @@ class RefreshOnChangeTest {
     fun testRefreshOnChange_updatesOnMatchingEvent() =
         runTest(testDispatcher) {
             val viewModel = TestViewModel()
-            // Let the init coroutine run so the collector actually subscribes
-            // before the event fires (replay=0 — events before subscription
-            // are dropped, matching production where VMs subscribe at
-            // construction and events arrive afterwards).
-            advanceUntilIdle()
-            ChangeEventHub.emit(WsEvent.ChangeEvent(ChangeEvents.CRON))
-            advanceUntilIdle()
-            assertEquals("refreshed", viewModel.state.value)
+            try {
+                // Let the init coroutine run so the collector actually subscribes
+                // before the event fires (replay=0 — events before subscription
+                // are dropped, matching production where VMs subscribe at
+                // construction and events arrive afterwards).
+                advanceUntilIdle()
+                ChangeEventHub.emit(WsEvent.ChangeEvent(ChangeEvents.CRON))
+                advanceUntilIdle()
+                assertEquals("refreshed", viewModel.state.value)
+            } finally {
+                viewModel.cleanup()
+            }
         }
 
     @Test
     fun testRefreshOnChange_ignoresOtherEventTypes() =
         runTest(testDispatcher) {
             val viewModel = TestViewModel()
-            advanceUntilIdle()
-            ChangeEventHub.emit(WsEvent.ChangeEvent(ChangeEvents.SESSIONS))
-            advanceUntilIdle()
-            assertEquals("initial", viewModel.state.value)
+            try {
+                advanceUntilIdle()
+                ChangeEventHub.emit(WsEvent.ChangeEvent(ChangeEvents.SESSIONS))
+                advanceUntilIdle()
+                assertEquals("initial", viewModel.state.value)
+            } finally {
+                viewModel.cleanup()
+            }
         }
 }
diff --git a/app/src/test/java/com/m57/hermescontrol/ui/sessions/SessionsViewModelTest.kt b/app/src/test/java/com/m57/hermescontrol/ui/sessions/SessionsViewModelTest.kt
index 1ec675fe..386d1871 100644
--- a/app/src/test/java/com/m57/hermescontrol/ui/sessions/SessionsViewModelTest.kt
+++ b/app/src/test/java/com/m57/hermescontrol/ui/sessions/SessionsViewModelTest.kt
@@ -281,4 +281,84 @@ class SessionsViewModelTest {
                 .contains("Pin failed"),
         )
     }
+
+    @Test
+    fun `displaySessions filters out hidden sessions by default and shows them on toggleShowHidden`() {
+        val vm = createViewModel()
+        coEvery { mockApi.getSessions(any(), any(), any()) } returns
+            Response.success(
+                SessionListResponse(
+                    sessions =
+                        listOf(
+                            SessionInfo("s-visible-1", hidden = false),
+                            SessionInfo("s-hidden", hidden = true),
+                            SessionInfo("s-visible-2", hidden = null),
+                        ),
+                    total = 3,
+                ),
+            )
+        vm.loadSessions()
+        testDispatcher.scheduler.advanceUntilIdle()
+
+        assertTrue(vm.uiState.value.hasHiddenSessions)
+        assertFalse(vm.uiState.value.showHidden)
+        assertEquals(
+            listOf("s-visible-1", "s-visible-2"),
+            vm.uiState.value.displaySessions
+                .map { it.id },
+        )
+
+        vm.toggleShowHidden()
+        assertTrue(vm.uiState.value.showHidden)
+        assertEquals(
+            listOf("s-visible-1", "s-hidden", "s-visible-2"),
+            vm.uiState.value.displaySessions
+                .map { it.id },
+        )
+
+        vm.toggleShowHidden()
+        assertFalse(vm.uiState.value.showHidden)
+        assertEquals(
+            listOf("s-visible-1", "s-visible-2"),
+            vm.uiState.value.displaySessions
+                .map { it.id },
+        )
+    }
+
+    @Test
+    fun `toggleHide updates hidden status and surfaces toast`() {
+        val vm = createViewModel()
+        coEvery { mockApi.getSessions(any(), any(), any()) } returns
+            Response.success(
+                SessionListResponse(
+                    sessions = listOf(SessionInfo("s-1", hidden = false)),
+                    total = 1,
+                ),
+            )
+        vm.loadSessions()
+        testDispatcher.scheduler.advanceUntilIdle()
+
+        coEvery { mockApi.setSessionHidden(any(), any()) } returns Response.success(Unit)
+        vm.toggleHide("s-1")
+        testDispatcher.scheduler.advanceUntilIdle()
+
+        assertEquals(
+            true,
+            vm.uiState.value.sessions
+                .first()
+                .hidden,
+        )
+        assertEquals("Session hidden", vm.uiState.value.toastMessage)
+
+        vm.toggleHide("s-1")
+        testDispatcher.scheduler.advanceUntilIdle()
+
+        assertEquals(
+            false,
+            vm.uiState.value.sessions
+                .first()
+                .hidden,
+        )
+        assertEquals("Session unhidden", vm.uiState.value.toastMessage)
+    }
 }